The present invention relates to the improvement of a toner recovery device for recovering the toner scraped off by the cleaning device designed to remove the toner remained on the image forming body after the transfer onto the recording paper of the image obtained by visualizing with the toner the electrostatic latent image formed on the image forming body such as the photosensitive drum by the electrophotographic recording device or electrostatic recording device.
In the cases of the electrophotographic duplicating machine and the electrostatic recording machine utilizing the electrostatic latent image, the electrostatic latent image is formed on the photosensitive drum, and the electrostatic latent image is visualized with the toner development device so that the image formed with the toner is transferred and fixed onto the recording paper to obtain the desired recorded image.
In said cases, the residual electric charge on the photosensitive drum which has once been used for the transfer of the toner image is neutralized by the charge-removing electrode, and the residual toner on the photosensitive drum is scraped off by the cleaning device to be ready for forming the next electrostatic latent image thereon.
In the case of said development device, about 70% of the toner supplied from the toner supplier is consumed for visualizing the image, and the rest of 30% is removed from the surface of the photosensitive drum by the cleaning device. Then, the used toner removed from the surface of the photosensitive drum is once collected into the toner collector in the duplicating machine and then carried into the collected toner container through the conveyance pipe.
Thus, in the conventional toner recovery device, recovered toner container is provided separately from the feed toner container. Thus, the recovered toner container is designed to be capable of directly connected to and disconnected from the stationary toner conveyance pipe communicating with the cleaning device. In this case, the toner conveyance pipe is provided with a shutter designed to operate simultaneously with the connecting and disconnecting actions of the conveyance pipe to prevent the toner from spilling from the outlet at the end of the pipe (Refer to Japanese Patent Publication Open to Public Inspection Nos. 134273/86, 6679/86 and 93480/86). In the case of the above-described conventional toner recovery device, however, the recovered toner container is separated from the feed toner container, and this caused the operator of the duplicating machine to tend to forget the change of the recovered toner container when changing the feed toner container. As a result, the recovered toner fills up the container until spilling from the container to contaminate around by the time of the next change of the feed toner container. Thus, recently the toner recovery device wherein the feed toner container and the recovered toner container are combined into a unit has been developed.
In the case of such a unitized toner recovery device, however, the location of the recovered toner container is limited due to the location of the feed toner container. As a result, the recovered toner container is required to be located above the development device, so that the cleaning device and recovered toner container need to be connected with a long toner conveyance pipe. Besides, the toner conveyance pipe is required to be removable to make easier the replacement of the recovered toner container, but there has been no appropriate device to prevent the toner from spilling outside from the outlet at the end of the pipe.
In consideration of said shortcoming of the conventional toner recovery device, it is the first object of the present invention to provide a toner recovery device of a simple construction characterized by that the outlet of the toner conveyance pipe can be closed when the pipe is brought to the point of disconnection to prevent the spill of the toner.
The relationship between the toner conveyance pipe and the recovered toner container in a conventional toner recovery is shown in FIG. 11(a) through (d) to clarify the problem of the conventional toner recovery device. FIG. 11(a) shows a conveyance pipe P passing vertically through the center of the top of a recovered toner container C so that the recovered toner T is accumulated into a conical shape in the recovered toner container C. FIG. 11(b) shows the case where the conveyance pipe P passes through the left side wall of the recovered toner container C so that the recovered toner is accumulated forming a slope. FIG. 11(c) and (d) show the cases where the conveyance pipe P is connected to an opening C' provided at the top of the recovered toner container C so that the toner T conveyed by the conveyance pipe P is accumulated into an asymmetrical conical shape.
The cause for the toner to be accumulated in a conical shape or in a slope lies in the problem concerning the conveyance pipe P itself. More particularly, in the case of the conventional conveyance pipe P, a screw member S is passed longitudinally through inside of the pipe member so that the toner can be forced forward as the screw member turns to carry the toner into the recovered toner container C. In this mechanism, however, there is the possibility that the toner gradually deposits on the internal wall surface near the outlet of the conveyance pipe as the conveying force decreases until to block the smooth flow of the toner, which may end up with the break of the screw in the extreme case.
Because of the reasons discussed above, in either of the above-described cases, the packing capacity of the recovered toner container becomes unstable, thereby causing the toner to spill from the opening of the container before the container is filled up with the toner. Thus, in order to overcome such problems, the conventional toner recovery device is provided with a photoelectric detector to monitor the condition of the toner near the entrance of the recovered toner container so that some appropriate vibration can be given to the recovered toner container to level the surface of the toner when the toner is accumulated in conical shape or in an asymmetric conical shape.
In consideration of the above-described problem, the second object of the present invention is to provide a toner recovery device improved in the efficiency in conveying the toner through the conveyance pipe and the efficiency in carrying the toner into the recovered toner container.